1. Field of the Invention
The present invention is generally directed to a narrowband communication system, and more particularly to a channel management technique for providing asymmetric wideband data services with a narrowband communication system.
2. Background Information
The allocation of frequency spectrum, available to a given communication system, is currently controlled on a worldwide, country by country, basis. As such, the amount of frequency spectrum that is available to a given communication system (e.g., satellite and terrestrial-based cellular) can potentially limit the capacity of the system. For example, a typical satellite communication system allocates channels for voice services, low-speed data services and system overhead channels (e.g., broadcast and acquisition channels) in a primary service band. Currently, there is a demand to use such systems for other services, such as, high-speed data services. However, implementing high-speed data services can significantly impact the ability of the communication system to carry primary services, such as voice subscriber traffic, in regions with heavy peak traffic.
Interlacing wideband data services, with narrowband services, can create channel and connection management problems that are not normally experienced when only narrowband services (e.g., voice services) are provided. Additional capacity needed for wideband services is virtually non-existent in the primary service band of most conventional narrowband communication systems, due to the amount of frequency spectrum already consumed by voice services, low-speed data services and system overhead channels.
Due to the limited bandwidth of most narrowband communication systems, it is also difficult to find spectrum in which to allocate channels in a handoff cell such that true make-before-break handoffs can be accomplished, when wideband services that utilize multiple narrowband channels are provided. In particular, if there are more than a few high-speed data terminal subscribers in a local region, the task becomes increasingly difficult.
Many high-speed data terminals require a guaranteed minimum bandwidth, because of the application in which they are used. For example, U.S. government regulations require a guaranteed bandwidth for a communication system that offers aeronautical safety data services. An aeronautical safety data terminal may function as a flight recorder and provide flight data on an airplane in which it is located. This flight data may be routed through a satellite constellation, of a communication system, to an appropriate ground station. The aeronautical safety data terminal may also communicate weather related information and facilitate airplane-to-airplane communication. Unfortunately, current narrowband communication systems typically lack the ability to provide reliable guaranteed service to such high-speed data terminals.
Additionally, the communication chipset of a high-speed data terminal can become quite complex when the receiver of the terminal is required to tune across a wide range of frequencies.